Firmware versions v3.10 and above work for the U3S kit ONLY (these versions do NOT work with the AD9850 DDS).

Since the launch of the first version in November 2013, there have been a number of new versions providing more functionality and sometimes including bug fixes. Since v3.02c, the firmware requires an ATmega328 microcontroller (formerly the ATmega168 was used). The firmware version files are hosted by the QRP Labs groups.io forum. An inexpensive AVR programmer can be used to upgrade your firmware version, or you can buy the latest firmware chip from QRP Labs.

- Introduces 16 transmission settings, each with their own mode, frequency, power, band.- Support for the relay-switched low pass filter board kit. - Support for “auxiliary” outputs, to control other relays or external circuits e.g. switched attenuators. - Several pairs of related configuration parameters are now shared into one screen. - Added new animation that is displayed during frequency calibration. - Bug fix: factory reset had moved to the left button. It is now correctly back on the right button. - Bug fix: factory reset left all mode settings blank, rather than “None”.

v3.02b

29.Jan.2014

- Bug fix: clock ran slowly when not using GPS (workaround: set Sys Freq low).- Bug fix: Calibration frequency was not accurately at 6.25MHz after cycling through the menu.- Bug fix: Right button click during calibration caused inaccurate calibration.

v3.02c

01.Feb.2014

- Bug fix: calibration was inaccurate by a few Hz up and down randomly.- Bug fix: calibration consistently resulted in too low transmission frequency.- Bug fix: inconsistent heartbeat, some beats were missed.- To fix bugs: flashing heart during Cal, Aux, and Cal animation, are temporarily disabled.- NOTE: THIS VERSION USES ATMEGA328 CHIP, IT DOES NOT FIT IN AN ATMEGA168 ANY MORE!

v3.03

07.Mar.2014

- Each transmission mode setting can be toggled enable/disable (disable looks “crossed out”)- Mode 0 no longer needs to be populated with valid data – disabled mode settings can be empty- Heartbeat always flashes for 0.25s in sync with detected 1pps event, even during calibration- Calibration progress is now indicated by a status bar animation- The error check now checks all of the enabled mode settings [0] to [F]- The Aux setting is now re-enabled- Switch-on: when GPS is enabled, does not transmit until valid GPS time has been set- Switch on: no calibration until after first transmission sequence (allows warm-up drift to subside)- Bug fix: No Hell mode message error, if Hell modes are used in mode settings other than [0]

- Bug fix: All WSPR messages were encoded with the same (last) power, not individually specified

v3.04

02.Jun.2014

- improve accuracy of wspr tone spacing: was 1.43, now 1.46Hz - toggle back and forth between "WSPR" and locator, in WSPR mode run display; show each for 3 tones' duration - Forces CalTime to 10 if in non-HP calibrate mode - Limits CalTime at 250 seconds maximum - WSPR freq is now the centre freq, not baseline (i.e. base frequency is 2.2Hz lower than U3 set/displayed frequency) - Put back "relay chatter", i.e. don't lock relay closed, on "Tune" (leave lock-on feature for TX to stop relay chatter) - Factory reset check, "Reset? Sure? Press left btn!" to prevent accidental reset - Allow blank locator when GPS enabled; the sytem waits indefinitely for a valid locator to be set - Bug fix: pressing left button in message edit, on the first blank character, entered a Null not a space - Bug fix: if the callsign was incorrect for WSPR, it reported it as a frequency error

v3.05

27.Aug.2014

- Support for Extended WSPR (callsign prefix/suffix, 6-char locator)- Change TX mode to TX CW and add new TX FSK mode- Locator display in WSPR15 as well as WSPR- Facility to tune the U3 using a potentiometer (requires hardware modification)- Backlight control from configuration menu (requires simple hardware modification)- Display the new calibrated reference frequency, and change from the old one, after a calibration- Diagnostic mode on first startup, to help troubleshooting (1Hz and 2Hz signals on alternating pins)- Bug fix: in some cases, time setting could allow incorrect characters e.g. letters etc- Bug fix: aux functionality did not work; also, now allows setting Aux to full hex range i.e. 0-F

- Support for U3S (Si5351 synthesiser module) as well as AD9850 DDS module - x2 feature, to drive LF PA's requiring double frequency drive - Frequency fields have 9 digits, to allow 2m band operation (Si5351A) - “EEPROM-saver”: only save calibrated frequency value if it has changed by more than a threshold

v3.08

24.Apr.2015

- Added support for JT9 modes (Si5351A only, not AD9850 DDS) - Message parameter can now be divided into sub-messages using delimiter character - Support various #-tags embedded in messages - Added Park modes support for Si5351A, can significantly reduce frequency drift - Speed parameter split into three, for CW, Slow modes (QRSS) and Slow-Hell - All invalid message characters for a given mode, are now simply sent as a space - Support for non-HP calibration method is discontinued - Move x2 and Ext WSPR settings to a combined 5-setting configuration screen - Configurable number of Mode screens appear in the menu now (default 3) - Potentiometer tuning mod now needs to be enabled in configuration, if used - Park mode 4, in Si5351A, now leaves the Park Freq permanently on Clk1 output - Additional digit for Park Frequency, which in Si5351A can be 1-150MHz - New flag “Invert” output, produces a 180-degree (inverse) output on Clk1 output - Switch “S3” on pin 27 can now be used to create a shifted dah in CW mode, kind of manual DFCW - Editing of messages improved, can now insert a character, and enter without going to end of msg - Bug fix: PI4 mode was shifted 250Hz when using Si5351A, starting in v3.07 - 1Hz and WSPR DDS shifts now held in EEPROM, so non-125MHz DDS could be used - An “Off” relay output is now tri-stated, not put into high (+5V) state – so 11-band mod works - Added “Altitude” to GPS Info display

- Bug fix: Custom messages: state variable not properly cleared on entering menu, could be stuck in custom etc - Bug fix: Custom messages: after space (key-up) the next custom symbol does not key-down again - Bug fix: Custom messages: the timing of the first custom symbol was wrong - Bug fix: Message display in slow CW modes e.g. FSKCW does not display if Fast CW speed is 25wpm or more - Bug fix: GPS mode 3 was still selectable when editing GPS mode(only 0, 1, 2 are valid) - Bug fix: Manual TX could mistakenly transmit as another mode, because an internal state variable wasn't reset - Bug fix: display during carrier part of PI4 kept the last character of the locator subsquare e.g. the G in "PI4 GCarrier" - Bug fix: Factory reset did not properly reset the contents of the EEPROM in some cases - Bug fix: Hell modes sent all punctuation messages as a space

- Bug fix: When using AD9850 DDS in U3, system locked when using more than 1 WSPR transmission

v3.11

11-Nov-2016

- New "RX" mode for using U3S with the Receiver kit; with IF offset - New parameter "PTT Delay" with function to use "Key" output as a "PTT" with configurable delay - Some text shortened to save space - Removed "Time" configuration coming at the start of the menu list when WSPR is enabled (U2 legacy feature) - Big fix: analogue value 1000 reported incorrectly by message tags e.g. #A1 etc

v3.12

03-Jan-2017

- new parameter "Shaping {ms Max}" to configure raised cosine generation when using PA kit (see AN004) - Convert Si5351A configuration and tone step algorithms to integer only - Changed Backlight parameter to {Bright Timeout}, timeout specified in seconds, 1..999 seconds (0 means no timeout) - When in extended WSPR mode, send the two WSPR pieces sequentially, not one each alternate cycle - Write EEPROM version ID last when doing a factoryReset, so that if interrupted it repair at next power up - Removed flicker during GPS calibration when backlight control used and at full brightness - Reference frequency defaults to 27,004,000 to be close to the usual crystal frequency

v3.12a

28-Jul-2017

- Bug fix: fix v3.12 issue where TX CW and TX FSK do not work at all- Bug fix: Implement short delay after pressing right button to exit config menu, to avoid keying the output by mistake- Bug fix: In "Iv" mode, the Clk1 output was always active (not keyed with Clk0) - Bug fix: In "Iv" mode, the Clk1 output was not deactivated when editing the configuration menu - Bug fix: in "Iv" mode, the Clk0 and Clk1 phase outputs were random, not 180 degrees as they should be